Refactor dtsi files

config/base.keymap

@@ -1,6 +1,5 @@
 #include <behaviors.dtsi>
 #include <dt-bindings/zmk/keys.h>
-#include <dt-bindings/zmk/mouse.h>
 
 #define XXX &none
 #define ___ &trans
@@ -14,6 +13,10 @@
 #define FN 4
 #define UC 5
 
+#include "mouse.dtsi"
+#include "unicode.dtsi"
+#include "combos.dtsi"
+
 /* create stubs if undefined */
 #if !defined EXTRA_MID
     #define EXTRA_MID
@@ -31,11 +34,11 @@ TODOs and ISSUES
  * tap-only combos not yet possible (#544), prevents rapid chaining of HRMs
  * &bootloader doesn't work with Planck_rev6 (#1086)
  * no global-quick-tap for combos
- * mouse wheel keys not yet implemented (#319), using up/down for now
  * mod-taps getting stuck with heterogenous combo-terms (#986, #905)
  * sticky-hold swallows OS shift when typing quickly, using sticky-tap for now
  * native sleep key doesn't work with windows (#1077), using sleep-macro for now
  * no native unicode support (#232), using preprocessor workaround instead
+ * no native mouse keys (#319), using mouse PR #778
  * mod-morph doesn't swallow mod (#686), using masked-mod PR #1114
 */
 
@@ -56,9 +59,6 @@ TODOs and ISSUES
 /* root node */
 / {
 
-    #include "unicode.dtsi"
-    #include "combos.dtsi"
-
     macros {
         // Windows sleep key
         win_sleep: win_sleep {